Presidents have often turned to foreign policy after domestic setbacks - from Ronald Reagan's Latin American tour and speech calling the Soviet Union the "focus of evil in the modern world" in the months after his party's 1982 congressional losses to Bill Clinton's escape to Indonesia and the Philippines following his own midterm trouncing a dozen years later. Both found redemption at the polls.

President Obama has followed suit. But since his midterm shellacking this month, he has suffered a series of foreign policy setbacks, in Congress and abroad, that have put his agenda for improving America's standing and strength overseas at risk.

From failing to secure a free-trade agreement in South Korea to struggling to win Senate ratification of an arms-control treaty with Russia, Obama has bumped up against the boundaries of his power at a defining moment of his presidency.

He is halfway through his term and politically weaker after midterm voters punished his party. But ahead are a host of unresolved foreign policy issues, from drawing down troops in Afghanistan to advancing Middle East peace prospects and economic relations with China, that will require a firm base of domestic support and could help determine whether he is reelected.

Obama arrived Friday morning in Lisbon for a NATO summit, where he hopes to secure military and financial commitments through 2014 from his allies in the Afghanistan war. But shadowing the meeting is Obama's early pledge to take on the world's most vexing issues and the lack of lasting progress achieving those goals.

"He assumed that because he was liked so clearly and overwhelmingly he could merely assert what he wanted to achieve and people would follow," said Simon Serfaty, a senior adviser at the Center for Strategic and International Studies. "Clearly enough, the world that he imagined proved to be different than the world as it is."

Presidents often look abroad after elections not only to avoid domestic troubles if they went against them but also because foreign affairs usually came second during months of campaigning.

Compelled in part by the fixed dates of two economic summits, Obama left for an extended trip to Asia just days after voters handed the House back to Republicans and narrowed the Democrats' majority in the Senate.

Although he found some adoring audiences in Asia, especially in his childhood home of Indonesia, Obama also encountered foreign leaders skeptical of his free-trade ambitions, proposals to address China's undervalued currency and U.S. monetary policies designed to promote growth at home.

A number of other issues have collided, as well, in a way that has highlighted how much of his foreign policy agenda remains incomplete.

The Middle East peace process he inaugurated two months ago has stalled. His mercurial ally in Afghanistan, President Hamid Karzai, is calling for scaled-back U.S. military operations there at the height of the 30,000-troop escalation Obama approved a year ago.

His pledge to remedy one polarizing legacy of the Bush administration by closing the U.S. detention center at Guantanamo Bay, Cuba, suffered this week when a jury convicted the first former detainee to face civilian trial on only one of 285 criminal counts.

Ben Rhodes, the deputy national security adviser for strategic communications, said "it would be a mistake to overly conflate" the midterm results and the resistance Obama is facing on several important foreign policy issues.

"The president remains a very respected and strong figure on the global stage," Rhodes said. "That's borne out in the esteem he's held in by foreign publics and by his relationships with world leaders. That's borne out by the way the United States sets the agenda in international forums, as is certainly the case with the NATO summit this weekend, and in the new relationship he's building with countries such as India."

He noted that Iraq's leadership recently formed a new government, eight months after elections, after Obama's attention and steady lobbying by such senior administration figures as Vice President Biden.

"At any given time in national security, there's issues where there is positive momentum and there are moments when there are challenges," Rhodes said. "I think it's a mistake to cherry-pick these to fit some narrative."

Much of what Obama achieved in Asia, most notably improved relations with India and its growing middle-class market, were the result of moves he could make on his own.

He endorsed India's bid for a seat on an expanded U.N. Security Council, for example, and waived export controls making it harder for Indian high-tech companies to do business with the United States.

Obama's trouble has come when he has needed a partner to get what he wants.

Israeli Prime Minister Binyamin Netanyahu has agreed to lobby for an additional three-month freeze on West Bank settlement construction in an attempt to get direct talks with the Palestinians back on track.

But in return, Obama, who has called Israeli settlements in the occupied territories "illegitimate," has agreed to not ask Netanyahu for a further extension if this one is approved and to press Congress to quickly approve $3 billion in military sales to Israel.

Obama placed his prestige behind the talks at their September launch, only to see them founder a few weeks later when Israel's 10-month settlement moratorium expired and building continued on land Palestinians envision as part of their future state.

National security analysts say the price Obama is willing to pay for another three months of talks is high, in part because he set a one-year timeline for their successful conclusion. Many believe that the deadline, like other of Obama's foreign policy goals, was overly optimistic.

At home, Obama is relying on the Senate to further his efforts to reset relations with Russia.

On his last day in Asia, Obama told Russian President Dmitry Medvedev on the sidelines of an economic summit that ratification of the New START agreement was a top priority in the lame-duck Congress.

That pact, to replace the Strategic Arms Reduction Treaty that expired last year, would continue to allow U.S. officials to monitor the Russian nuclear arsenal and shrink the number of deployed warheads. At a White House meeting Thursday, Obama called the treaty "a national security imperative."

But emboldened Senate Republicans, led by Sen. Jon Kyl (Ariz.), say they have not been given enough time to consider the treaty despite it being signed seven months ago. Obama has pledged billions of dollars in additional funds to address Kyl's concern that the U.S. arsenal needs to be modernized, but he is short of the 67 Senate votes he needs.

A senior European diplomat in Washington said "you will see repercussions on Iran, you will see repercussions on Afghanistan, you will see repercussions on the Middle East" if the Senate declines to ratify the treaty, given how much support Russia gives the Obama administration on those issues.

"I would not see so much a weakening of Obama - I would see a weakening of the United States," the diplomat said. "If the world sees the United States is not in a position to ratify a treaty very much in its benefit . . . the United States would lose standing."

Richard Haass, the president of the Council on Foreign Relations who held senior foreign-policy positions in both Bush administrations, said "it's no big deal if gets kicked off until February, March, then passes."

"You don't want to bring this to a vote and lose," Haass said. "You don't want to have the Senate equivalent of going to Seoul and not getting a trade agreement."

Serfaty said Obama is burdened by "a sense of the deflated expectations of the past two years."

Unfairly or not, he said, Obama was expected to do more on nuclear arms reduction and nonproliferation issues, more to advance peace in the Middle East, and more to resolve the conflicts in Iraq and Afghanistan.

"That's what has exploded over the past two or three weeks more visibly," he continued. "Over that time, wherever you turn, you feel there is a great deal of confusion and too much of an attempt to patch up and come up with a quick win, as if on every single issue the credibility of the administration is on the line."